1. Field of the Invention
The present invention is directed toward venting an aspiration path in a peristaltic pump after an unacceptably high vacuum level is reached and in particular to air venting.
2. Description of Related Art
During the use of a peristaltic pump, particularly during ophthalmic surgery an occlusion of the aspiration path (including a surgical hand piece, aspiration tubing, a pump cartridge, and a collection bag) may occur. Once a piece of tissue, such as a piece of cataract, blocks the aspiration port of the surgical hand piece, such as a phacoemulsification instrument, a vacuum level in the aspiration path begins to rise. If the occlusion is not timely removed the vacuum level may become dangerous, in that after the occlusion is removed, there may be an excessive surge through the aspiration path causing the eye to collapse and the intraocular pressure (IOP) in the eye to suddenly and dramatically drop. This can cause serious damage to the eye.
Thus, it is well known in the art to vent the aspiration path to ambient pressure to relieve a vacuum buildup before it becomes too dangerous. Typically, this is accomplished by connecting a short length of tubing at one end to the aspiration path and letting the other end be exposed to the ambient air of the operating room. This short length of tubing is typically held within a pump cartridge and is pinched shut by a pinch valve. When a surgeon wants to air vent the line he activates a switch to remove the pinch valve from the tubing thus allowing ambient air to relieve the vacuum that was built up. This requires the pump to include an expensive pinch valve exclusively for the purpose of air venting.
Therefore, it would be desirable to have a pump that would allow for air venting without the need for an extra pinch valve.